l0 = [1]
l1 = [1,1]
l2 = [1,2,1]
l3 = [1,3,3,1]
l4 = []
for x in range(len(l3)):
    if x == 0:
        l4.append(1)
    else:
        l4.append(l3[x]+l3[x-1])
l4.append(1)
print(l4)
